• Geotechnical Engineering
• /
• v.1 no.2
• /
• pp.81-92
• /
• 1985

Braced excavation for a new building was carried out at a very close proximity of an existing tall building of T.hick columns are supported by indict.ideal spread footings on sand layer The excavation was planned to reach far below the footing level of the existing building. To assess the foundation performance and stability of the existing building, the behavior of 9round subjected to loss of confinement from excavation was analytically studied using finite element method. Field instrumentation was also conducted to monitor the actual ground responses during excavation. Based on these studies, various remedial measures weere taken to minimize the adverse effects to the building, and excavation was successfully completed. This paper presents the results from the analytical studies and field monitoring, and measured and measured responses at different stages of excavation.

• Journal of the Korean GEO-environmental Society
• /
• v.16 no.2
• /
• pp.27-31
• /
• 2015

In urban area, many design projects related to geotechnical projects are controlled by serviceability rather than stability requirements. Accordingly, control of ground deformation has become more crucial and many researchers have studied soil stiffness. Recent experimental studies on the stress-strain response of Chicago glacial clays showed that the nonlinearity and anisotropy are the two key factors in evaluating the soil stiffness. In this study, experimental results are applied to analyze the deep excavation site locating in downtown Chicago. The stress paths observed from the observation points located behind and front of the supporting wall yield typical stress paths. Changes in soil stiffness nonlinearity and anisotropy were discussed by comparing experimental and computed stress paths. The stiffness anisotropy were significant even at the first few excavations. The stiffness degradation characteristics are significantly different according to relative location to the support wall even at the same elevation.

• The Journal of Engineering Geology
• /
• v.12 no.1
• /
• pp.1-21
• /
• 2002

Recently, the rapid industrialization and urbanization of the country due to a high economic growth, require optimization, usage and the expansion of underground space. Therefore the consturction of large and deep basements takes place in braced excavated area where their earth retaining structures cause many problems such as settlement and damages of nearby buildings and underground utilities. this study deals with the influence distance of settlement and the amount for settlement based on the measurement which were obtained at five excavation construction sites. Maximum ground surface settlement, (0.28∼0.3)(%)H utilizing depth, is similar to the measurement and the value by Clough's method. It was found that the settlement and the influence distance of settlement calculated by Clough's method were rational.

• Journal of the Korean GEO-environmental Society
• /
• v.10 no.3
• /
• pp.63-71
• /
• 2009

The movement of in-situ walls has become very important as construction in large cities moves upward, instead of outward. Tall structures typically have deep excavations not on1y to provide extra space for parking, but also to reduce the potential settlement of the building. These large excavations require a robust bracing system to resist the lateral earth pressures as the depth increases. Methods to predict deflections of the retaining systems are of utmost importance because wall movements allow potentia1 settlement of adjacent structures. Case studies will be analyzed and measured waI1 def1ections will be compared with predictions from empirica1ly derived charts.

• Geotechnical Engineering
• /
• v.13 no.2
• /
• pp.101-124
• /
• 1997

Adjacent ground surface settlements by deep excavations are analyzed by field observations in the areas where excavations are performed in sandy soils or weathered soils underlain by rocks, First, the magnitude and the distribution of ground surface settlements, which are developed before main excavation activities (e. g., diaphragm wall installation and center pile installation) , are measured and analyzed. Secondly, the magnitude and the distribution of ground surface settlements by main excavation are measured and analyzed. And the results are compared with the predictions obtained by the empirical methods. Through case studies performed on the excavation sites where adjacent ground surfaces or structures are damaged by excavation activities, upper limit location of ground surface cracks are investigated.

• Journal of the Korean Geotechnical Society
• /
• v.19 no.5
• /
• pp.15-26
• /
• 2003

Urban excavation requires highly reliable prediction technique for the design and construction of earth retaining structure in order to protect adjacent structures around deep excavation. Application of the pre-loading of bracing for deep excavation has been reported, and the known beneficial effects are not fully understood and recognized by many practitioners. Model tests have been carried out to evaluate the efficiency of pre-loading system in reducing ground settlement as well as prediction of structural damage around excavation in sand. The test results revealed that the applied pre-loading of 50% and 70% showed about 20% of reduction in horizontal wall displacement and 30∼40% reduction in ground settlement. Also, bracing forces and earth pressure distribution behind the wall have been monitored during pre-loading at various excavation stages.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1996.10a
• /
• pp.25-38
• /
• 1996

• Proceedings of the Korean Geotechical Society Conference
• /
• 1998.06b
• /
• pp.59-72
• /
• 1998

• Geotechnical Engineering
• /
• v.2 no.1
• /
• pp.79-84
• /
• 1986

• Journal of the Korean Geotechnical Society
• /
• v.26 no.7
• /
• pp.171-186
• /
• 2010

It is generally known that the mechanism of behavior in the flexible earth retaining system is relatively more complicated than in the rigid earth retaining system. Moreover in the case of long span strut supporting system the analysis of strut axial force change becomes more difficult when the differences of ground condition and excavation work progress on both sides of excavation section are added. When deeper excavation than the specification or installation delay of supporting system or change of ground condition happen during construction process, lots of axial force can be induced in some struts, which threaten the safety of construction. This paper introduces two examples of long span deep excavation where struts and rock bolts were used as a supporting system with flexible wall structure. The characteristics of ground deformation and strut axial force change, which were measured in the sections of two examples that are 50 meters apart in one construction site and have almost similar design and construction conditions were analysed, the similarity and difference between measurement results of two examples were compared and investigated. This article aims to improve and develop the technique of design and construction in future projects having similar ground condition and supporting method.